Neal McDonough is suiting up for USA's Suits and the actor is bound to stir up trouble on the legal drama. McDonough plays Sean Cahill, an SEC investigator who is tasked to uncover any issues at Pearson Specter and will stop at nothing until he brings the firm down. McDonough first appears in this Wednesday's episode titled "Leveraged." Suits airs Wednesdays, 9 p.m. on USA.